Moisture-Curable Hot-Melt Adhesive Agent

ABSTRACT

There are provided a moisture curable hot melt adhesive excellent in balance among initial adhesion strength, post curing adhesion strength and heat resistance, and a layered product formed by bonding with that moisture curable hot melt adhesive agent. The moisture-curable hot melt adhesive comprises a urethane prepolymer having an isocyanate group at the end (A), a styrene based block copolymer (B), and an urethane modified rosin (C), wherein the urethane modified rosin (C) is a reaction product of a rosin derivative having hydroxyl group and an isocyanate compound.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims benefit under Article 4 of the Paris Conventionbased on Japanese Patent Application No. 2017-106259 filed in Japan onMay 30, 2017, incorporated herein by reference in its entirety.

TECHNICAL FIELD

The present invention relates to a moisture-curable hot-melt adhesiveagent.

BACKGROUND

A hot-melt adhesive agent is being used in various fields of buildinginterior materials (or construction materials) and electronic materials.Particularly, the moisture-curable hot-melt adhesive agent is drawingattention because it is less likely to be affected by external factorsand is easily used for a long period of time.

Examples of the moisture-curable hot-melt adhesive agent include anadhesive agent that comprises an urethane prepolymer having anisocyanate group at the end. The moisture-curable hot-melt adhesiveagent is commonly applied in a hot molten state to at least one of asubstrate and an adherend and cooled and solidified for initialadhesion. Then, the isocyanate group is cross-linked with moisture inatmospheric air to cause moisture curing and thus allow the urethaneprepolymer to increase molecular weight thereof, so that themoisture-curable hot-melt adhesive agent is improved in adhesion forceand heat resistance.

Initial adhesion strength is one of performance characteristics requiredof the moisture-curable hot-melt adhesive agent. In order to increasethe initial adhesion strength, a tackifier resin is blended in themoisture-curable hot-melt adhesive agent to increase initial wettabilityto a substrate, or a thermoplastic resin is blended to improve initialaggregation force.

The tackifier resin and the thermoplastic resin, however, are not alwayssufficient in compatibility with the urethane prepolymer as a maincomponent of the moisture-curable hot-melt adhesive agent.

Further, there have been problems of operation that a time (open time)that is until the moisture-curable hot-melt adhesive agent is curedafter its application is excessively short to cause difficult operation,and viscosity of the adhesive agent is excessively increased to causedifficult application.

Patent Documents 1 to 3 disclose moisture-curable hot-melt adhesiveagents comprising an urethane prepolymer and a thermoplastic resin. Themoisture-curable hot-melt adhesive agent in any of the documentscomprises an urethane prepolymer and a styrene based copolymer.Hereinafter, the disclosure of Patent Documents 1 to 3 is specificallydescribed.

Patent Document 1 describes a reactive hot-melt adhesive agentcomposition comprising as main components an urethane prepolymer and athermoplastic rubber composition (claim 1). Patent Document 1 provides,as the moisture-curable hot-melt adhesive agent, a reactive hot-meltadhesive agent composition that is improved in compatibility with athermoplastic rubber by producing the urethane prepolymer with use of aprepolymer of a long-chain polyether having 6 or more carbon atoms andis thus excellent in compatibility, moisture-curability andadhesiveness.

Patent Document 1 discloses, as the thermoplastic rubber, astyrene-ethylene/butylene-styrene (SEBS) block copolymer (Example 1) anda styrene-butadiene-styrene (SBS) copolymer (Comparative Example 1).Patent Document 1 also discloses using as a tackifier an aliphatic basedcyclic hydrocarbon (Example 1).

Patent Document 2 describes that, in a reactive hot-melt adhesive agentcomposition formed of an urethane prepolymer and a styrene basedcopolymer rubber, a polyester polyol is used as a polyether componentfor synthesis of the urethane prepolymer not to allow adhesion force tosignificantly decrease at 50 to 60° C. and thus to improve initialadhesion force.

Patent Document 2 discloses as the styrene based copolymer rubber, anSBS block copolymer (Example 1) and an SEBS block copolymer (Example 2).Patent Document 2 also discloses using as a tackifier resin an alicyclicsaturated hydrocarbon (Example 1) and a terpene-styrene resin (Example2).

Patent Document 3 describes that, in a reactive hot-melt adhesivecomposition comprising as main components an urethane prepolymer and athermoplastic rubber component, a saturated hydrocarbon based polyolhaving a hydroxyl group at both terminals is used to give abundantcompatibility with the thermoplastic rubber component and improvetoughness and weather resistance such as non-yellowing.

Patent Document 3 discloses as the thermoplastic rubber component astyrene-isoprene-styrene (SIS) block copolymer in Table 1. The SIS isblended in an amount of 19 to 35 parts by weight of the urethanemodified resin (C), based on 100 parts by weight of the urethaneprepolymer and the SIS. Patent Document 3 also discloses using as atackifier a hydrogenated dicyclopentadiene based petroleum resin(Example 1).

Patent Documents 1 and 2 give moisture-curable hot-melt adhesive agentsbad in balance between initial adhesion strength and heat resistance,and Patent Document 3 gives a moisture-curable hot-melt adhesive agentremarkably low in initial adhesion strength.

When an addition amount of the tackifier resin is adjusted to improveinitial adhesion strength of the moisture-curable hot-melt adhesiveagent, the adhesive agent that has been taken care of (cured) decreasesits adhesion strength. As described above, it is difficult to produce amoisture-curable hot-melt adhesive agent excellent in balance amongvarious performance characteristics. Customers, however, are requiring amoisture-curable hot-melt adhesive agent excellent in balance amongperformance characteristics.

Accordingly, in recent years, a moisture-curable hot-melt adhesive agentis required to be rapidly developed that is excellent in balance amonginitial adhesion strength, adhesion strength of the adhesive agent thathas been taken care of (cured), and heat resistance.

BACKGROUND ART DOCUMENTS

Patent Document 1: Japanese Patent Laid-open Publication No.H02(1990)-212576

Patent Document 2: Japanese Patent Laid-open Publication No.H06(1994)-128552

Patent Document 3: Japanese Patent Laid-open Publication No.H02(1990)-272013

SUMMARY OF INVENTION Problems to be Solved by the Invention

The present invention is achieved to solve the problems described above,and an object of the present invention is to provide a moisture-curablehot-melt adhesive agent excellent in balance among initial adhesionstrength, post-curing adhesion strength and heat resistance, and alayered product obtained by bonding with the moisture-curable hot-meltadhesive agent.

Means for Solving the Problems

The present invention provides a moisture-curable hot-melt adhesiveagent comprising:

an urethane prepolymer having an isocyanate group at the end (A);

a styrene based block copolymer (B); and

an urethane modified rosin (C),

wherein

the urethane modified rosin (C) is a reaction product of a rosinderivative having hydroxyl group and an isocyanate compound.

In one embodiment, the rosin derivative having hydroxyl group is esterof rosin and polyhydric alcohol.

In one embodiment, the rosin derivative having hydroxyl group has ahydroxyl value of 2 to 180 mg KOH/g.

In one embodiment, the moisture-curable hot-melt adhesive agent isformed by comprising the urethane modified rosin (C) in an amount of 20to 80 parts by weight of the urethane modified resin (C), based on 100parts by weight in total of (A) and (B).

In one embodiment, any one of the moisture-curable hot-melt adhesiveagents described above further comprises a hydrocarbon resin (D).

The present invention also provides a layered product comprising:

a substrate;

an adhesive layer formed on a surface of the substrate; and

an adherend adhered to a surface of the adhesive layer,

wherein

the adhesive layer consists of any one of the moisture-curable hot-meltadhesive agents described above.

The present invention also provides a method for producing amoisture-curable hot-melt adhesive agent, the method comprising a stepof mixing an urethane modified rosin (C) obtained by a reaction of anisocyanate compound and a rosin derivative having hydroxyl group, astyrene based block copolymer (B), a polyol and an isocyanate compound.

In one embodiment, the method gives an urethane prepolymer (A) by mixingthe polyol and the isocyanate compound.

Effects of the Invention

The moisture-curable hot-melt adhesive agent according to the presentinvention is improved in initial adhesion strength, post-curing adhesionstrength and heat resistance with good balance, is excellentparticularly in initial adhesion strength at a temperature widelyranging from 5° C. to 35° C., and exhibits excellent initial adhesionstrength at any of normal temperature (spring and summer), lowtemperature (winter) and high temperature (summer).

The moisture-curable hot-melt adhesive agent according to the presentinvention is excellent in balance among performance characteristics, isapplied to various substrates regardless of a season or a warm or coldregion, and may contribute to efficient production of many types oflayered products.

EMBODIMENTS FOR CARRYING OUT THE INVENTION

First described are technical terms used in the present specification.

The “open time” refers to a time from application of a moltenmoisture-curable hot-melt adhesive agent to an adherend until theadhesive agent does not show fluidity and is not capable of wetting asurface of the adherend.

The “initial adhesion strength” refers to adhesion strength of themoisture-curable hot-melt adhesive agent that has been melted andapplied to an adherend and then solidified at low temperature. Theinitial adhesion strength is affected by wettability and aggregationforce. The initial adhesion strength is preferred to be large.

The “wettability” may be measured when the moisture-curable hot-meltadhesive agent that has been heated and melted is brought into contactwith a substrate (solid), specifically by size of an angle (α) of an endportion of the molten adhesive agent with respect to the substrate incontact with the molten adhesive agent. The smaller the α is, the largerthe wettability is and the easier the adhesion is.

The “aggregation force” refers to force attributed to mutual actionamong molecules in a heated and melted moisture-curable hot-meltadhesive agent that is generated in a cooling process after applicationof the adhesive agent with an applicator.

Next described is the moisture-curable hot-melt adhesive agent accordingto the present invention.

Urethane Prepolymer Having an Isocyanate Group at the End (A)

The moisture-curable hot-melt adhesive agent according to the presentinvention comprises an urethane prepolymer having an isocyanate group atthe end (A) (hereinafter, also described as a “component (A)”). Theurethane prepolymer having an isocyanate group at the end (A) is notparticularly limited as long as it is normally understood as a “urethaneprepolymer,” is a “urethane prepolymer having an isocyanate group at theend,” and is capable of giving an intended moisture-curable hot-meltadhesive agent.

Such an urethane prepolymer is obtained by reacting a polyol and anisocyanate compound according to a known method.

In the present specification, the “polyol” is not particularly limitedas long as it is capable of giving an intended urethane prepolymer, andas the “polyol,” a publicly known polyol may be used that is utilizedfor normally producing polyurethane. The polyol preferably has 1 to 3functional groups and is particularly preferred to be a bifunctionalpolyol, i.e., a diol. A polyol may be used alone, or polyols may be usedin combination. Examples of the diol include low-molecular-weight diolssuch as ethylene glycol, 1-methylethylene glycol, 1-ethylethyleneglycol, propylene glycol, butanediol, pentanediol, hexanediol,heptanediol, octanediol, nonanediol, decanediol, neopentyl glycol,2-methyl-1,3-propanediol, cyclohexane dimethanol and2,4-dimethyl-1,5-pentanediol. Preferred is at least one selected fromethylene glycol, butanediol, hexanediol, octanediol and decanediol.These diols may be used alone or in combination.

As the “polyol” in the present invention, a polyether polyol and apolyester polyol are also exemplified.

Examples of the polyether polyol include polyoxytetramethylene glycol(PTMG), polyoxypropylene glycol (PPG) and polyoxyethylene glycol (PEG).Particularly preferred as the polyether polyol is polyoxypropyleneglycol.

Examples of the polyester polyol in the present invention include anaromatic polyester polyol and an aliphatic polyester polyol.

The aromatic polyester polyol is preferably obtained by a reaction of anaromatic carboxylic acid and a diol. Examples of the aromaticpolycarboxylic acid include phthalic acid, isophthalic acid,terephthalic acid and hexahydroisophthalic acid. These may be usedalone, or two or more of them may be used in combination. As one exampleof the aromatic polyester polyol, exemplified are a polyalkylenephthalate, a polyalkylene isophthalate and a polyalkylene terephthalatethat each have an OH terminal. Particularly preferred as the aromaticpolyester polyol is a polyalkylene phthalate having an OH terminal.

The aliphatic polyester polyols may be obtained by a reaction of analiphatic carboxylic acid and a diol. Examples of the aliphaticcarboxylic acid include adipic acid, sebacic acid, azelaic acid anddecamethylene dicarboxylic acid. These may be used alone, or two or moreof them may be used in combination. As one example of the aliphaticpolyester polyol, exemplified are polyhexamethylene adipate (PHMA) andpolybutylene adipate (PBA) that each have an OH terminal. Particularlypreferred as the aliphatic polyester polyol is polyhexamethylene adipatehaving an OH terminal.

In the present invention, a particularly preferred aspect of the polyolis an aliphatic polyester polyol. As to the aliphatic polyester polyol,a single polyol may be used alone, or different two or more polyols maybe used in combination.

Number average molecular weight of the polyol is not particularlylimited but is preferably from 1,000 to 7,000. In the presentspecification, weight average molecular weight or number averagemolecular weight is obtained by use of gel permeation chromatography(GPC) and conversion of a result of the GPC into molecular weight usinga calibration curve prepared for a standard substance, i.e., polystyrenehaving monodispersed molecular weight.

The isocyanate compound in the present invention is not particularlylimited as long as it is capable of giving an intended urethaneprepolymer, and any isocyanate compound is acceptable that is used fornormally producing polyurethane. The isocyanate compound preferably hasan average of 1 to 3 isocyanate groups per molecule and is particularlypreferred to be a bifunctional isocyanate compound, i.e., a diisocyanatecompound. An isocyanate compound may be used alone, or two or moreisocyanate compounds may be used in combination.

Examples of the “isocyanate compound” include ethylene diisocyanate,ethylidene diisocyanate, propylene diisocyanate, butylene diisocyanate,hexamethylene diisocyanate, toluene diisocyanate,cyclopentylene-1,3-diisocyanate, cyclohexylene-1,4-diisocyanate,cyclohexylene-1,2-diisocyanate, 4,4′-diphenylmethane diisocyanate,2,2′-diphenylpropane-4,4′-diisocyanate, p-phenylene diisocyanate,m-phenylene diisocyanate, xylylene diisocyanate, 1,4-naphthylenediisocyanate, 1,5-naphthylene diisocyanate, diphenyl-4,4′-diisocyanate,azobenzene-4,4′-diisocyanate, diphenyl sulfone-4,4′-diisocyanate,dichlorohexamethylene diisocyanate, furfurylidene diisocyanate and1-chlorobenzene-2,4-diisocyanate. The isocyanate compounds may be usedalone or in combination.

When the “urethane prepolymer” of the present invention is produced, amonool or a monoisocyanate compound may be used as long as it is capableof giving an intended urethane prepolymer. While a trifunctional polyoland a trifunctional isocyanate may be used, it is at least preferred toproduce the urethane prepolymer with use of a bifunctional polyol (diol)and a bifunctional isocyanate compound (diisocyanate compound). It ismore preferred to produce the “urethane prepolymer” by a reaction of abifunctional polyol with a bifunctional isocyanate compound from theview point of heat stability of the moisture-curable hot-melt adhesiveagent to be obtained and control of the production method (andproduction steps of the method).

In order to produce the urethane prepolymer having an isocyanate groupat the end (A), the polyol is mixed with the isocyanate compound so asto give a molar ratio (NCO/OH) between an NCO group and an OH group ofpreferably 1.3 (lower limit) or more, more preferably 2 or more, andpreferably 3 (upper limit) or less. It is preferred to use about 2 mol(approximately 1.8 mol to 2.3 mol) of a bifunctional isocyanate based on1 mol of a bifunctional polyol because such a ratio allows production ofan intended urethane prepolymer comparatively easily.

Styrene Based Block Copolymer (B)

The moisture-curable hot-melt adhesive agent according to the presentinvention comprises a styrene-isoprene based block copolymer (B)(hereinafter, also described as a “component (B)”). The styrene basedblock copolymer (B) is a copolymer obtained by copolymerization ofstyrene as a vinyl based aromatic hydrocarbon and a conjugated dienecompound and is a resin composition normally comprising something formedof a styrene block and a conjugated diene compound block.

The moisture-curable hot-melt adhesive agent according to the presentinvention comprises the styrene based block copolymer (B) to maintain abalance among heat resistance, initial adhesion strength and post-curingadhesion strength and to be excellent particularly in heat resistance.

The “conjugated diene compound” means a diolefin compound having atleast a pair of conjugated double bonds. Specific examples of the“conjugated diene compound” include 1,3-butadiene,2-methyl-1,3-butadiene (or isoprene), 2,3-dimethyl-1,3-butadiene,1,3-pentadiene and 1,3-hexadiene. Particularly preferred are1,3-butadiene and 2-methyl-1,3-butadiene. These conjugated dienecompounds may be used alone or in combination.

The styrene based block copolymer (B) of the present invention may be anunhydrogenated product or a hydrogenated product.

The “unhydrogenated product of the styrene based block copolymer (B)”specifically refers to a styrene based block copolymer whose conjugateddiene compound block is not hydrogenated.

The “hydrogenated product of the styrene based block copolymer (B)”specifically refers to a block copolymer whose conjugated diene compoundblocks are entirely or partially hydrogenated.

Proportion of hydrogenation in the “hydrogenated product of the styrenebased block copolymer (B)” may be represented by “percentage ofhydrogenation.” The “percentage of hydrogenation” of the “hydrogenatedproduct of the styrene based block copolymer (B)” refers to proportionof a double bond that has been hydrogenated and converted into asaturated hydrocarbon bond in all aliphatic double bonds as a referencethat are contained in the conjugated diene compound block. The“percentage of hydrogenation” may be measured by an infraredspectrophotometer and a nuclear magnetic resonance apparatus.

Specific examples of the “unhydrogenated product of the styrene basedblock copolymer (B)” include a styrene-isoprene-styrene block copolymer(“SIS”) and a styrene-butadiene-styrene (block copolymer “SBS”).

Specific examples of the “hydrogenated product of the styrene basedblock copolymer (B)” include a styrene-ethylene/propylene-styrene blockcopolymer (“SEPS”) and styrene-ethylene/butylene-styrene (“SEBS”).

The styrene based block copolymer (B) may be any of a radial type, alinear type and a triblock type as long as it does not impair the objectof the present invention.

In the present invention, the styrene based block copolymer (B)preferably comprises a styrene based block copolymer having a styrenecontent rate of 15% by weight or more, particularly preferably comprisesboth a styrene based block copolymer having a styrene content rate of 15to 35% by weight (B1) and a styrene based block copolymer having astyrene content rate of 40 to 70% by weight (B2).

The hot-melt adhesive agent according to the present invention comprisesthe styrene based block copolymer having a styrene content rate of 15%by weight or more to be more excellent in balance among initial adhesionstrength, post-curing adhesion strength and heat resistance andcomprises both the (B1) and the (B2) to be excellent at a higher levelin balance among initial adhesion strength, post-curing adhesionstrength and heat resistance.

In the present invention, the (B1) comprises a styrene-isoprene basedblock copolymer, and the (B2) more preferably comprises astyrene-isoprene based block copolymer.

In the present specification, the “styrene content rate” refers toproportion of the styrene block contained in the styrene based blockcopolymer (B).

In the present invention, the styrene based block copolymer having astyrene content rate of 15 to 35% by weight (B1) has a diblock contentrate of preferably 30 to 70% by weight, most desirably 35 to 60% byweight.

In the present specification, the styrene based block copolymer having astyrene content rate of 40 to 70% by weight (B2) has a diblock contentrate of preferably less than 40% by weight, particularly desirably 30%by weight or less, most desirably 0% by weight. The styrene based blockcopolymer (B2) having a diblock content rate of 0% by weight is atriblock copolymer.

In the present specification, the “diblock content rate” refers toproportion of a styrene-conjugated diene compound block copolymercontained in the (B). The diblock is represented by the followingformula (1).

[Chemical Formula 1]

S-E   (1)

(S represents a styrene block, and E represents a conjugated dienecompound block.)

As the styrene based block copolymer (B) of the present invention, acommercially available product may be used.

Examples of the (B1) include Asaprene T432 (manufactured by Asahi KaseiCorp.) as a styrene-butadiene-styrene block copolymer; and QuintacSL-165 (manufactured by Zeon Corporation), VECTOR 4411A (manufactured byDexco), VECTOR 4211A (manufactured by Dexco), Quintac 3270 (manufacturedby Zeon Corporation), Quintac 3460 (manufactured by Zeon Corporation),Quintac 3433N (manufactured by Zeon Corporation) and Quintac 3450(manufactured by Zeon Corporation) as a styrene-isoprene-styrene blockcopolymer.

Examples of the (B2) include Asaprene T439 (manufactured by Asahi KaseiCorp.) as a styrene-butadiene-styrene block copolymer; and KRATON D1162(manufactured by Kraton Corporation), Quintac 3390 (manufactured by ZeonCorporation) and Quintac SL-168 (manufactured by Zeon Corporation) as astyrene-isoprene-styrene block copolymer.

The components of these commercially available products may each be usedalone or may be used in combination of two or more components.

Urethane Modified Rosin (C)

The moisture-curable hot-melt adhesive agent according to the presentinvention comprises an urethane modified rosin (C) (hereinafter, alsodescribed as a “component (C)”). The urethane modified rosin (C) refersto a modified rosin obtained by reacting an “isocyanate compound” and a“rosin derivative having hydroxyl group.” The “rosin derivative havinghydroxyl group” refers to a derivative obtained by modifying a rosin soas to have a hydroxyl group. For example, a reaction of a rosin and adiol bonds a carboxyl group of the rosin with one hydroxyl group of thediol by an ester bond to give a rosin derivative having hydroxyl group.

The urethane modified rosin (C) is obtained by reacting a hydroxyl groupcontained in the rosin derivative and the isocyanate compound. Thehydroxyl group of the rosin derivative reacts with an isocyanate groupto form an urethane bond. Accordingly, the urethane modified rosin (C)does not substantially have a hydroxyl group not to substantially reactand an isocyanate compound. It is preferred that the urethane modifiedrosin (C) do not substantially have an isocyanate group.

Accordingly, at the time of producing the moisture-curable hot-meltadhesive agent, even when the urethane modified rosin (C) is added to amixture of the polyol and the isocyanate compound that form theprepolymer, the urethane modified rosin (C) does not substantiallyaffect a reaction of the polyol and the isocyanate compound to eliminatethe need for excessively adding an isocyanate compound. This makes themoisture-curable hot-melt adhesive agent comprising the “urethanemodified rosin (C)” of the present invention described above excellentin balance among initial adhesion strength, post-curing adhesionstrength and heat resistance, particularly excellent in post-curingadhesion strength.

In the present invention the “urethane modified rosin (C)” refers to amodified rosin that is obtained by a reaction of a rosin derivativehaving hydroxyl group and an isocyanate compound and contains in itsmolecule an urethane bond formed by a reaction of a hydroxyl group andan isocyanate group. For production of the urethane modified rosin (C),a diol may further be used that has a weight average molecular weight of1000 or less.

The “rosin derivative having hydroxyl group” is as described above. Therosin derivative, however, is more specifically ester of rosin andpolyhydric alcohol, a formalin-modified rosin or a modified rosinalcohol, for example, and refers to a rosin derivative having aremaining hydroxyl group. The rosin derivative having hydroxyl group hasa hydroxyl value of commonly 2 to 180 mg KOH/g, preferably 4 to 80 mgKOH/g, more preferably 6 to 40 mg KOH/g.

The rosin derivative having a hydroxyl value in the ranges describedabove makes the moisture-curable hot-melt adhesive agent according tothe present invention more excellent in balance among initial adhesionstrength, post-curing adhesion strength and heat resistance.

The “rosin derivative having hydroxyl group” of the present inventionhas a remaining hydroxyl group as a result of various types ofmodification performed on a rosin, and ester of rosin and polyhydricalcohol is exemplified as a most common rosin derivative having hydroxylgroup.

Examples of the “rosin” include unmodified rosins such as a gum rosin, awood rosin and a tall oil rosin as well as disproportionated rosins,hydrogenated rosins and polymerized rosins based on these rosins, andpurified products of these rosins. It is also possible to use reinforcedrosins obtained by adding to these rosins maleic acid, maleic anhydride,fumaric acid and acrylic acid as well as modified products of theserosins.

Examples of the polyhydric alcohol include dihydric alcohols such asethylene glycol, propylene glycol, diethylene glycol and dipropyleneglycol, trihydric alcohols such as glycerin and trimethylolpropane,tetrahydric alcohols such as pentaerythritol and diglycerin, andhexahydric alcohols such as dipentaerythritol.

The ester of a rosin and a polyhydric alcohol (hereinafter, alsoreferred to as a “rosin ester”) may be obtained by a known method. Forexample, the ester may be obtained by heating a rosin and an alcohol inan inert atmosphere such as nitrogen gas. This process is performedunder the reaction conditions of commonly 250 to 280° C. and 5 to 20hours.

The production method may also be applied for a formalin-modified rosinand a modified rosin alcohol, and further for a rosin on which isperformed modification such as phenolation.

The “isocyanate compound” as a raw material for the urethane modifiedrosin may be identical or different from the “isocyanate compound”described for the production of the “urethane prepolymer.” The“isocyanate compound” as a material for the urethane modified rosin isacceptable as long as the compound has at least one isocyanate group,and may be a monoisocyanate or a diisocyanate. The isocyanate compoundmay also be an isocyanate to which a polyhydric alcohol is added.

In the moisture-curable hot-melt adhesive agent according to the presentinvention, the contents of the components (A), (B) and (C) may bedefined on the basis of a total 100 parts by weight of the urethaneprepolymer having an isocyanate group at the end (A) and thestyrene-isoprene based block copolymer (B). That is, the contents are asfollows:

component (A): commonly 25 to 85 parts by weight, preferably 30 to 70parts by weight, more preferably 40 to 60 parts by weight; and

component (C): commonly 25 to 90 parts by weight, preferably 30 to 80parts by weight, more preferably 38 to 78 parts by weight.

The urethane modified rosin (C) having a content in the ranges describedabove allows the moisture-curable hot-melt adhesive agent according tothe present invention to maintain a balance among heat resistance,initial adhesion strength and post-curing adhesion strength and makesthe adhesive agent particularly excellent in post-curing adhesionstrength.

Hydrocarbon Resin (D)

In the present invention, the hydrocarbon resin (D) is not particularlylimited as long as it consists of only carbon and hydrogen and iscapable of giving the moisture-curable hot-melt adhesive agent intendedin the present invention.

Examples of the hydrocarbon resin (D) include a natural rosin, ahydrogenated rosin, a copolymer of a natural terpene, a terpolymer of anatural terpene, a hydrogenated derivative of a copolymer of ahydrogenated terpene, a polyterpene resin, a hydrogenated derivative ofa phenol based modified terpene resin, an aliphatic petroleumhydrocarbon resin, a hydrogenated derivative of an aliphatic petroleumhydrocarbon resin, an aromatic petroleum hydrocarbon resin, ahydrogenated derivative of an aromatic petroleum hydrocarbon resin, acyclic aliphatic petroleum hydrocarbon resin and a hydrogenatedderivative of a cyclic aliphatic petroleum hydrocarbon resin. Thesehydrocarbon resins may be used alone or in combination.

As the hydrocarbon resin (D), a commercially available product may beused. Examples of such a commercially available product include MARUKACLEAR H (trade name) manufactured by Maruzen Petrochemical Co., Ltd.,CLEARON K100 (trade name), CLEARON K4090 (trade name) and CLEARON K4100(trade name) manufactured by YASUHARA CHEMICAL CO., LTD., ARKON M100(trade name) manufactured by ARAKAWA CHEMICAL INDUSTRIES, LTD., I-MARV5100 (trade name) manufactured by Idemitsu Kosan Co., Ltd., T-REZ HA103(trade name), T-REZ HA125 (trade name) and T-REZ HC103 (trade name)manufactured by TonenGeneral Sekiyu K.K., and Regalite R7100 (tradename) manufactured by Eastman Chemical Company. These commerciallyavailable hydrocarbon resins may be used alone or in combination.

Plasticizer (E)

The moisture-curable hot-melt adhesive agent according to the presentinvention preferably comprises a plasticizer (E) in addition to thecomponents (A) to (C). The plasticizer (E) allows the moisture-curablehot-melt adhesive agent to maintain somewhat low viscosity while theplasticizer (E) improves compatibility of the components (A) to (C). Themoisture-curable hot-melt adhesive agent is low in viscosity and thus isexcellent in coatability to increase wettability to an adherend, so thatthe initial adhesion strength is improved.

In the present invention, the plasticizer (E) is not particularlylimited as long as it is normally used and is capable of giving themoisture-curable hot-melt adhesive agent intended in the presentinvention.

Examples of the plasticizer (E) include a paraffin based oil, anaphthene based oil, an aromatic based oil, dioctyl phthalate, dibutylphthalate, dioctyl adipate and mineral spirit.

As the plasticizer (E), a commercially available product may be used.Examples of the commercially available product include White Oil Broom350 (trade name) manufactured by Kukdong Oil & Chemicals Co., Ltd.,Diana Fresia S32 (trade name), Diana Process Oil PW-90 (trade name) andDN Oil KP-68 (trade name) manufactured by Idemitsu Kosan Co., Ltd.,Enerper M1930 (trade name) manufactured by BP Chemicals Ltd., Kaydol(trade name) manufactured by Crompton Corporation, Primol 352 (tradename) manufactured by Esso, Process Oil NS100 manufactured by IdemitsuKosan Co., Ltd., and KN4010 (trade name) manufactured by PetroChinaCompany Limited. These plasticizers (E) may be used alone or incombination.

The moisture-curable hot-melt adhesive agent according to the presentinvention may comprise another additive as necessary. The “additive” isnot particularly limited as long as it is normally used for amoisture-curable hot-melt adhesive agent and may be used for themoisture-curable hot-melt adhesive agent according to the presentinvention. Examples of such an additive include a plasticizer, anantioxidant, a pigment, a photostabilizer, a flame retardant, a catalystand a wax.

Examples of the “antioxidant” include a phenol based antioxidant, aphosphite based antioxidant, a thioether based antioxidant and an aminebased antioxidant.

Examples of the “pigment” include titanium oxide and carbon black.

Examples of the “photostabilizer” include benzotriazole, hindered amine,benzoate and benzotriazole.

Examples of the “flame retardant” include a halogen based flameretardant, a phosphorous based flame retardant, an antimony based flameretardant and a metal hydroxide based flame retardant.

Examples of the “catalyst” include metal based catalysts such as tinbased catalysts (trimethyltin laurate, trimethyltin hydroxide,dibutyltin dilaurate and dibutyltin maleate), lead based catalysts (leadoleate, lead naphthenate and lead octenoate) and other metal basedcatalysts (naphthenic acid metal salts such as cobalt naphthenate), andamine based catalysts such as triethylenediamine,tetramethylethylenediamine, tetramethylhexylenediamine,diazabicycloalkenes and dialkylaminoalkylamines.

Examples of the “wax” include waxes such as a paraffin wax and amicrocrystalline wax.

A method for producing the moisture-curable hot-melt adhesive agentaccording to the present invention is acceptable as long as it includesa step of mixing the components (A) to (C), the components (D) and (E)as necessary, and various additives, and is not particularly limited interms of an order and a method of mixing the components. One or both ofthe polyol and the isocyanate compound for obtaining the urethaneprepolymer (A) may be simultaneously mixed with the styrene based blockcopolymer (B) and the urethane modified rosin (C), or the polyol may bereacted with the isocyanate compound in advance to produce the urethaneprepolymer (A), followed by mixing the urethane prepolymer (A) with theother components (B) and (C).

The urethane modified rosin (C) is preferably synthesized before it ismixed with the urethane prepolymer (A). Such preparation does not allowthe “rosin derivative having hydroxyl group” or the “isocyanate” as araw material for the urethane modified rosin (C) to react with the“polyol” or the “isocyanate compound” as a raw material for the urethaneprepolymer (A). This allows the moisture-curable hot-melt adhesive agentaccording to the present invention to certainly comprise the urethanemodified rosin (C), so that the moisture-curable hot-melt adhesive agentmay maintain a good balance among heat resistance, initial adhesionstrength and post-curing adhesion strength.

The moisture-curable hot-melt adhesive agent according to the presentinvention may be produced by heating, melting and mixing the componentsmutually. For example, the moisture-curable hot-melt adhesive agent maybe produced by charging the components into a stirrer-equipped meltingmixing pot and heating and mixing the components.

The moisture-curable hot-melt adhesive agent obtained as described aboveis a reactive hot-melt adhesive agent, is a solid at room temperature,and may be used according to a usual method for a reactive hot-meltadhesive agent. Commonly, the moisture-curable hot-melt adhesive agentis heated and melted for use.

Layered Product

A layered product according to the present invention includes themoisture-curable hot-melt adhesive agent described above. The layeredproduct is produced by laminating a surface of a “substrate” and an“adherend” with use of the moisture-curable hot-melt adhesive agentaccording to the present invention. When the layered product isproduced, the moisture-curable hot-melt adhesive agent may be applied tothe substrate, the adherend or both the substrate and the adherend.Materials and forms of the substrate and the adherend may be identicalor different.

The “substrate” is not particularly limited, and the following areexemplified, for example:

woody materials such as plywood (e.g., lauan plywood), a medium densityfiberboard (MDF), a particle board, solid wood and a woody fiber board;

inorganic materials such as a cement board, a gypsum board andautoclaved lightweight concrete (ALC); and

plastic materials such as polyethylene terephthalate, polycarbonate,polyurethane, polyethylene and polypropylene.

The form of the “substrate” is not also particularly limited and isacceptable as any of a molded resin form, a film form and a sheet form.

As the “adherend,” any normally used material is acceptable, and theadherend is not particularly limited. Specific examples of the adherendinclude a film and a sheet.

The film may be colorless or colored and transparent or opaque. Examplesof the film include films made from a polyolefin resin, a polyesterresin, an acetate resin, a polystyrene resin and a vinyl chloride resin.Examples of the polyolefin resin include polyethylene and polypropylene.Examples of the polyester resin include polyethylene terephthalate.

The adherend may be a decorative sheet. As the decorative sheet, thefollowing are exemplified, for example:

sheets made from plastic materials such as a vinyl chloride resin, apolyolefin resin and a polyester resin that are rigid or semirigid;

sliced veneer prepared by processing wood into a sheet form; and

decorative paper provided with various decorative prints.

The layered product according to the present invention is applicable tovarious uses, specifically for a building material, furniture, anelectronic material and an automobile field, for example.

The layered product may be produced with use of commonly knownproduction apparatuses including a carrier machine, a coater, a pressingmachine, a heater and a cutting machine, without using a specialapparatus.

For example, the layered product may be produced as follows. Themoisture-curable hot-melt adhesive agent according to the presentinvention is applied to the substrate or the adherend with a coaterwhile the substrate and the adherend are carried by a carrier machine. Aheater is controlled at a predetermined temperature when the applicationis performed. The adherend is lightly pressed against the substrate witha pressing machine to be adhered to the substrate with themoisture-curable hot-melt adhesive agent interposed between the adherendand the substrate. Then, the adhered adherend and substrate is allowedto cool and directly carried by a carrier machine to solidify themoisture-curable hot-melt adhesive agent. Then, the substrate having theadherend adhered thereto is cut with a cutting machine into anappropriate size.

The moisture-curable hot-melt adhesive agent according to the presentinvention is high in initial adhesion strength, sufficient inpost-curing adhesion strength, and excellent in heat resistance, so thatthe layered product according to the present invention is a product thatis efficiently produced and is excellent in various qualities.

EXAMPLES

Hereinafter, the present invention is described by way of examples andcomparative examples. These examples, however, are for describing thepresent invention and do not limit any of the present invention.

Components for producing the hot-melt adhesive agent are as follows.

Materials for constituting urethane prepolymer having an isocyanategroup at the end (A) (polyol component and isocyanate component)

Polyol Component

-   Polyester polyol (Al) (HS 2F-231AS (trade name) manufactured by    Hokoku Corporation, melting point 30° C., hydroxyl value 56 (mg    KOH/g))-   Polyester polyol (A2) (HS 2H-350S (trade name) manufactured by    Hokoku Corporation, melting point −5° C., hydroxyl value 32 (mg    KOH/g))-   Polyester polyol (A3) (HS 2E-581A (trade name) manufactured by    Hokoku Corporation, melting point −5° C., hydroxyl value 21 (mg    KOH/g))-   Polypropylene glycol (A4) (HIFLEX D-2000 (trade name) manufactured    by DKS Co. Ltd., hydroxyl value 56 (mg KOH/g))

Isocyanate Component

-   4,4′-diphenylmethane diisocyanate (A5) (Millionate MT (trade name)    manufactured by Tosoh Corporation)

Styrene Based Block Copolymer (B)

-   Styrene-ethylene-butylene block copolymer (B1-1) (G1657 (trade name)    manufactured by Kraton Corporation, styrene content rate 13% by    weight, diblock content rate 30% by weight, MFR 8 g/10 min: 200° C.)-   Styrene-isoprene block copolymer (B1-2) (JSR5403 (trade name)    manufactured by JSR Corporation, styrene content rate 15% by weight,    diblock content rate 40% by weight, MFR 20 g/10 min: 200° C.)-   Styrene-isoprene block copolymer (B1-3) (Quintac 3433N (trade name)    manufactured by Zeon Corporation, styrene content rate 16% by    weight, diblock content rate 56% by weight, MFR 12 g/10 min: 200°    C.)-   Styrene-isoprene block copolymer (B1-4) (Quintac 3270 (trade name)    manufactured by Zeon Corporation, styrene content rate 24% by    weight, diblock content rate 67% by weight, MFR 20 g/10 min: 200°    C.)-   Styrene-isoprene block copolymer (B1-5) (Quintac SL-165 (trade name)    manufactured by Zeon Corporation, styrene content rate 30% by    weight, diblock content rate 60% by weight, MFR 16 g/10 min: 200°    C.)-   Styrene-butadiene block copolymer (B1-6) (Asaprene T432 (trade name)    manufactured by Asahi Kasei Chemicals Corporation, styrene content    rate 30% by weight, diblock content rate 25% by weight, MFR 0.2 g/10    min: 200° C.)-   Styrene-isoprene block copolymer (B2-1) (D-1162 (trade name)    manufactured by Kraton Corporation, styrene content rate 43% by    weight, diblock content rate 0% by weight (triblock co-aggregate),    MFR 45 g/10 min: 200° C.)-   Styrene-butadiene block copolymer (B2-2) (Asaprene T439 (trade name)    manufactured by Asahi Kasei Chemicals Corporation, styrene content    rate 45% by weight, diblock content rate 62% by weight, MFR    undisclosed)-   Styrene-butadiene block copolymer (B2-3) (TR2250 (trade name)    manufactured by JSR Corporation, styrene content rate 52% by weight,    diblock content rate 0% by weight (triblock co-aggregate), MFR 4.0    g/10 min: 200° C.)-   Styrene-butadiene/butylene block copolymer (B2-4) (Tuftec P2000    (trade name) manufactured by Asahi Kasei Chemicals Corporation,    styrene content rate 67% by weight, diblock content rate 0% by    weight (triblock co-aggregate), MFR 3.0 g/10 min: 190° C.)-   Ethylene ethyl acrylate copolymer (B′3) (NUC6070 (trade name)    manufactured by NUC Corporation, ethyl acrylate content rate 25% by    weight, MFR 250 g/10 min: 190° C.)

Urethane Modified Rosin (C)

-   Urethane modified rosin (C1) (The production method is described    later (Table 1).)-   Urethane modified rosin (C2) (The production method is described    later (Table 1).)-   Urethane modified rosin (C3) (The production method is described    later (Table 1).)-   Urethane modified rosin (C4) (The production method is described    later (Table 1).)    Hydrocarbon resin (D)-   Unhydrogenated C5 resin (D1) (Wingtack 86 (trade name) manufactured    by Cray Valley, softening point 87° C.)-   Completely hydrogenated DCPD resin (D2) (T-REZ HA103 (trade name)    manufactured by TonenGeneral Sekiyu K.K., softening point 103° C.)-   Partially hydrogenated C9 resin (D3) (ARKON M100 (trade name)    manufactured by ARAKAWA CHEMICAL INDUSTRIES, LTD., softening point    100° C.)-   Completely hydrogenated C9 resin (D4) (ARKON P125 (trade name)    manufactured by ARAKAWA CHEMICAL INDUSTRIES, LTD., softening point    125° C.)

Plasticizer (E)

-   Naphthene oil (E1) (SUNPURE N90 (trade name) manufactured by JAPAN    SUN OIL COMPANY, LTD.)-   Paraffin oil (E2) (Daphne Oil KP68 (trade name) manufactured by    Idemitsu Kosan Co., Ltd.)-   Rice oil (E3) (rice salad oil (trade name) manufactured by Boso oil    and fat Co., Ltd.)

Other Additive (F)

-   Antioxidant (F1) (ADK STAB AO-60 (trade name) manufactured by ADEKA    Corporation)

Method for Producing Moisture-Curable Hot-Melt Adhesive Agent

A method for producing an urethane modified rosin is described below.

First, a rosin ester component (G) was charged into a reaction vesseland melted in an oven at 130° C., and then moisture was removed bystirring the component for 1 hour under reduced pressure while thereaction vessel was heated in oil bath at 130° C. Next, the isocyanatecomponent (A5) or (H1) was charged at an NCO/OH ratio of 1.05 andstirred for 1 hour under reduced pressure at 130° C. to give an urethanemodified rosin (C).

The urethane modified rosin was subjected to infrared spectroscopicspectrum analysis (FT-IR analysis), and it was confirmed that absorptionof 2300 cm⁻¹ by an isocyanate group and absorption of 3400 cm⁻¹ by ahydroxyl group were almost lost.

Combinations of rosin ester components with isocyanate components are asshown in Table 1.

TABLE 1 Urethane Combination modified rosin of components (C1) (G1) (A5)(C2) (G1) (H1) (C3) (G2) (H1) (C4) (G3) (H1)

Rosin Ester as Component for Constituting Urethane Modified Rosin (G)

-   Hydroxyl group-containing rosin ester resin (G1) (SYLVALITE RE85GB    (trade name) manufactured by Arizona Chemical Holdings Corporation,    softening point 85° C., hydroxyl value 25 (mg KOH/g))-   Hydroxyl group-containing rosin ester resin (G2) (SYLVALITE RE105L    (trade name) manufactured by Arizona Chemical Holdings Corporation,    softening point 105° C., hydroxyl value 10 (mg KOH/g))-   Hydroxyl group-containing rosin ester resin (G3) (SUPER ESTER T125    (trade name) manufactured by ARAKAWA CHEMICAL INDUSTRIES, LTD.,    softening point 125° C., hydroxyl value 7 (mg KOH/g))    Isocyanate as component for constituting urethane modified rosin (H)-   p-Toluene sulfonyl isocyanate (H1) (manufactured by Wako Pure    Chemical Industries, Ltd.)

Example 1

The components (A) to (E) were mixed to produce a moisture-curablehot-melt adhesive agent.

Specifically, the components (B1-5), (B2-1), (C1), (D3), (D4), (E1) and(F1) at the composition (parts by weight) indicated in Table 2 weremelted and mixed with a versatile stirrer over about 1 hour at about145° C. to prepare a molten composition.

Next, the polyester polyol (A3) was mixed with the molten composition atthe composition (parts by weight) indicated in Table 2, and this mixturewas put into a reaction vessel. The mixture was heated at 130° C. for 1hour and stirred for 1 hour under reduced pressure at the sametemperature. After it was confirmed that moisture was removed and themixture was sufficiently kneaded, the 4,4′-diphenylmethane diisocyanate(A5) was added and stirred for 1 hour under reduced pressure at the sametemperature to give a moisture-curable hot-melt adhesive agent.

Examples 2 to 9 and Comparative Examples 1 to 4

The components (A) to (E) were prepared by the same steps as in Example1 at the composition indicated in Tables 2, 4 and 6 to product amoisture-curable hot-melt adhesive agent.

The hot-melt adhesive agents of the examples and the comparativeexamples that were obtained as described above were measured for meltviscosity, heat resistance (creep test), initial adhesion strength(tack) and post-curing adhesion strength (durability test). Tables 3, 5and 7 show the results of the measurements.

TABLE 2 Classification Classification of raw of raw Classification ofmaterials 1 materials 2 raw materials 3 Example 1 Example 2 Example 3Example 4 Example 5 Urethane Polyol (A1) prepolymer (A2) 24.6 (A) (A3)57.5 53.3 19.2 56.9 45.4 (A4) 7.7 Isocyanate (A5) 5.7 6.1 3.8 5.6 7.0Styrene based Low styrene (B1-1) block content rate (B1-2) 16.8copolymer (B1) (B1-3) (B) (B1-4) 34.6 37.5 23.0 (B1-5) 14.7 (B1-6) Highstyrene (B2-1) 22.1 23.8 34.6 content rate (B2-2) (B2) (B2-3) (B2-4)Ethylene ethyl acrylate (B′ 3) copolymer Urethane modified rosin (C)(C1) 56.1 39.4 (C2) 73.7 (C3) 38.9 25.5 (C4) Hydrocarbon resin (D) (D1)41.7 24.6 (D2) 14.5 (D3) 10.5 (D4) 23.2 25.7 Plasticizer (E) (E1) 24.229.2 14.8 (E2) 14.9 (E3) 28.8 Additive (F) (F1) 0.4 0.4 0.4 0.4 0.4Hydroxyl group-containing (G1) rosin ester (G) Isocyanate (H) (H1)NCO/OH (ratio of functional group) 2.1 2.1 2.1 2.1 1.8 Total 210.9 191.1196.2 208.3 163.9

TABLE 3 Measurement item Example 1 Example 2 Example 3 Example 4 Example5 Viscosity (mPas) 33500 50300 53500 41750 98000 Creep (min) 9.6 6.8 3.32.3 3.1 Evaluation of heat resistance ⊚ ⊚ ◯ Δ ◯ Tack (g/cm²)  5° C. 31002560 3461 3003 2567 23° C. 3650 4100 4100 3900 2195 35° C. 4400 30004710 3330 2582 Evaluation of initial  5° C. ⊚ ◯ ⊚ ⊚ ◯ adhesion strength23° C. ⊚ ⊚ ⊚ ⊚ ◯ 35° C. ⊚ ⊚ ⊚ ⊚ ◯ Evaluation of post•curing ◯ ◯ ◯ ◯ ◯adhesion strength (durability)

TABLE 4 Classification of Classification of Classification of rawmaterials 1 raw materials 2 raw materials 3 Example 6 Example 7 Example8 Example 9 Urethane Polyol (A1) 32.0 36.6 prepolymer (A) (A2) 11.0 (A3)60.7 58.1 (A4) 11.4 Isocyanate (A5) 6.0 13.7 8.5 5.7 Styrene based Lowstyrene (B1-1) 42.9 block copolymer content rate (B1) (B1-2) 24.4 (B)(B1-3) (B1-4) (B1-5) 29.8 (B1-6) 11.1 High styrene (B2-1) content rate(B2) (B2-2) 22.2 (B2-3) 19.5 (B2-4) 6.4 Ethylene ethyl acrylatecopolymer (B′ 3) Urethane modified rosin (C)(C1) (C2) 36.4 78.0 (C3)23.0 63.3 44.1 (C4) 12.5 Hydrocarbon resin (D) (D1) 44.4 34.9 38.3 (D2)42.9 (D3) (D4) Plasticizer (E) (E1) 22.2 42.9 35.9 31.9 (E2) (E3)Additive (F) (F1) 0.4 0.4 0.4 0.4 Hydroxyl group-containing rosin (G1)ester (G) Isocyanate (H) (H1) NCO/OH (ratio of functional group) 2.1 2.51.6 2.1 Total 222.2 257.1 243.9 212.8

TABLE 5 Measurement item Example 6 Example 7 Example 8 Example 9Viscosity (mPas) 33250 56000 77000 83000 Creep (min) 6.3 1.2 4.8 6.5Evaluation of heat ⊚ Δ ◯ ⊚ resistance Tack (g/cm²)  5° C. 1720 7270 19202220 23° C. 2710 3969 2530 2630 35° C. 3380 6075 2980 3140 Evaluation of 5° C. Δ ⊚ Δ ◯ initial adhesion 23° C. ◯ ⊚ ◯ ◯ strength 35° C. ⊚ ⊚ ◯ ⊚Evaluation of ◯ ◯ ◯ ◯ post curing adhesion strength (durability)

TABLE 6 Classification Classification Classification of of raw of rawraw Comparative Comparative Comparative Comparative materials 1materials 2 materials 3 Example 1 Example 2 Example 3 Example 4 UrethanePolyol (A1) prepolymer (A2) 19.2 (A) (A3) 54.6 19.2 50.3 56.7 (A4) 7.7Isocyanate (A5) 5.4 3.8 7.4 5.6 Styrene based Low (B1-1) block styrene(B1·2) 37.8 copolymer (B) content rate (B1·3) (B1) (B1-4) 34.6 7.7(B1-5) (B1·6) High (B2·1) 34.6 15.4 styrene (B2·2) content rate (B2·3)(B2) (B2-4) Ethylene ethyl (B′ 3) 40.0 acrylate copolymer Urethanemodified rosin (C) (C1) (C2) (C3) 41.0 (C4) Hydrocarbon resin (D) (D1)32.0 (D2) 28.2 (D3) (D4) Plasticizer (E) (E1) 28.0 25.1 (E2) (E3) 28.8Additive (F) (F1) 0.4 0.4 0.4 0.4 Hydroxyl group-containing (G1) 97.8rosin ester (G) Isocyanate (H) (H1) 67.3 9.6 NCO/OH (ratio of functionalgroup) 2.1 2.1 2.1 2.1 Total 203.1 196.2 128.2 222.9

TABLE 7 Compar- Compar- Compar- Compar- ative ative ative ative ExampleExample Example Example Measurement item 1 2 3 4 Viscosity (mPas) 1000039000 Unmixed 20719 Creep (min) 0.5 6.0 — 3.5 Evaluation of X ⊚ X ◯ heatresistance Tack (g/cm²)  5° C. 2322 3750 — 2000 23° C. 3012 3520 — 280035° C. 2700 5750 — 3750 Evaluation of  5° C. ◯ ⊚ X ◯ initial adhesion23° C. ⊚ ⊚ X ◯ strength 35° C. ◯ ⊚ X ⊚ Evaluation of ◯ X X X post curingadhesion strength (durability)

Hereinafter, measurement methods and evaluation methods are described.

Melt Viscosity

Each of the moisture-curable hot-melt adhesive agents was evaluated forviscosity at 130° C. according to Method B of JAI7-1991. The measurementwas performed with a Brookfield viscometer (rotor No. 27).

Heat Resistance (Creep)

Used as a material for the test was a particle board (10.0 cm×10.0 cm×2cm) isothermalized in a thermostatic chamber at 25° C. for 12 hours ormore. The particle board was coated with each of the hot-melt adhesiveagents of the examples and the comparative examples with a roll coaterat a coating temperature of 130° C. Thickness of the adhesive agentapplied was 70±10 μm.

With the adhesive agent applied, a melamine board (13.0 cm×2.5 cm) wasadhered to the particle board. Specifically, the melamine board wasplaced so as to protrude from the particle board by 2 cm, and both theboards were adhered to each other with a roll pressing machine to give asample for the creep test.

This sample was immediately fixed to an upper portion of a thermostatictank at 80° C. The sample was fixed in such a manner that the 2 cmprotrusion of the melamine board came downside. The sample was preheatedfor 1 minute, then a 245 g weight was hung at the tab, or the 2 cmprotrusion (melamine board), and a time until the weight dropped wasmeasured to evaluate creep property.

The present test was performed for the purpose of evaluatingpre-reaction heat resistance (creep performance), and therefore theseries of procedures from the coating to the start of the measurementwas performed within 3 minutes.

The creep was evaluated by the time from the start of the measurementuntil the evaluation piece of the melamine board peeled and dropped.Evaluation criteria are as follows.

-   ⊚: 5.0 minutes or more-   ◯: 3.0 minutes or more and less than 5.0 minutes-   Δ: 1.0 minute or more and less than 3.0 minutes-   X: less than 1.0 minute

Initial Adhesion Strength (Tack)

A 50-μm-thick PET film was coated with each of the hot-melt adhesiveagents of the examples and the comparative examples at a thickness of 50μm, and the coated PET film was placed in a peltier type temperaturecontrol unit.

The tack measurement was performed with a tack tester (manufactured byUBM) having a 5 mmφ plunger set therein. The tack measurement wasperformed at a pressing pressure of 1.5 kg/cm², a pressing time of 1 secand a speed of plunger vertical movement of 10 mm/sec during the tackmeasurement.

The measurement was performed under the three temperature conditions formeasurement of 5° C., 23° C. and 35° C. The present test was performedfor the purpose of evaluating pre-reaction initial adhesion strength,and therefore the series of procedures from the coating to the start ofthe measurement was performed within 3 minutes.

Evaluation criteria for tack are as follows.

-   ⊚: 3000 g/cm² or more-   ◯: 2000 g/cm² or more and less than 3000 g/cm²-   Δ: 1000 g/cm² or more and less than 2000 g/cm²-   X: less than 1000 g/cm²

Post-Curing Adhesion Strength (Durability)

A material for the test was a particle board (10.0 cm×10.0 cm×2 cm)isothermalized in a thermostatic chamber at 25° C. for 12 hours or more.The particle board was coated with each of the hot-melt adhesive agentsof the examples and the comparative examples with a roll coater at acoating temperature of 130° C. Thickness of the adhesive agent appliedwas 70±10 μm.

With the adhesive agent applied, a melamine board (4.0 cm×10.0 cm) wasadhered to the particle board with a roll pressing machine to give asample. The sample was taken care of at room temperature for 1 week ormore and then left to stand still in a thermostatic tank at 60° C. Afterthe sample was left to stand still for 24 hours, it was taken out andvisually confirmed for generation of floating and peeling on themelamine board and the particle board.

Evaluation criteria for durability are as follows.

-   ◯: without either floating or peeling-   X: with floating or/and peeling

As shown in Tables 3 and 5, the moisture-curable hot-melt adhesiveagents of the examples are good in all of heat resistance (creep),initial adhesion strength (tack) and post-curing adhesion strength(durability). Particularly, the moisture-curable hot-melt adhesive agentof Example 1 is high in creep performance to be an index for heatresistance and is good in initial adhesion strength (tack) in a widerange of temperature from 5 to 35° C.

The moisture-curable hot-melt adhesive agents of the comparativeexamples are, as shown in Table 7, bad in balance among creep, tack anddurability and has a cross in any of the evaluation items.

Accordingly, it was demonstrated that the moisture-curable hot-meltadhesive agent is excellent in heat resistance, initial adhesionstrength and post-curing adhesion strength by comprising all thecomponents (A), (B) and (C).

INDUSTRIAL APPLICABILITY

The present invention provides a moisture-curable hot-melt adhesiveagent. The moisture-curable hot-melt adhesive agent according to thepresent invention is effective for producing a layered product forvarious uses, for example, for exterior and interior materials forbuilding materials, flooring, attachment of a decorative sheet to asubstrate, and profile wrapping.

1. A moisture curable hot melt adhesive comprising: a urethaneprepolymer having a terminal isocyanate group (A); a styrene based blockcopolymer (B); and an urethane modified rosin (C), wherein the urethanemodified rosin (C) is a reaction product of a rosin derivative having ahydroxyl group and an isocyanate compound.
 2. The moisture curable hotmelt adhesive according to claim 1, wherein the styrene based blockcopolymer (B) comprises a styrene based block copolymer having a styrenecontent of 15% and to 35% by weight (B1) and a styrene based blockcopolymer having a styrene content of 40% and to 70% by weight (B2). 3.The moisture curable hot melt adhesive according to claim 1, wherein thestyrene based block copolymer (B) comprises a styrene based blockcopolymer having a styrene content of 15% and to 35% by weight and adeblock content rate of 30% to 70% by weight (B1) and a styrene basedblock copolymer having a styrene content of 40% and to 70% by weight anda deblock content rate of 0% to less than 40% by weight (B2).
 4. Themoisture curable hot melt adhesive according to claim 1, wherein thestyrene based block copolymer (B) comprises a styrene based blockcopolymer having a styrene content of 15% and to 35% by weight (B1) anda styrene based triblock copolymer having a styrene content of 40% andto 70% by weight (B2).
 5. The moisture curable hot melt adhesiveaccording to claim 1, wherein the rosin derivative having a hydroxylgroup is an ester of rosin and a polyhydric alcohol.
 6. The moisturecurable hot melt adhesive according to claim 1, wherein the rosinderivative having a hydroxyl group has a hydroxyl value of 2 to 180 mgKOH/g.
 7. The moisture curable hot melt adhesive according to claim 1,comprising 20 to 80 parts by weight of the urethane modified rosin (C)based on 100 parts by weight in total of (A) and (B).
 8. The moisturecurable hot melt adhesive according to claim 1, wherein the urethanemodified rosin (C) is free of isocyanate groups.
 9. The moisture curablehot melt adhesive according to claim 1, further comprising a hydrocarbonresin (D).
 10. Cured reaction products of the moisture curable hot meltadhesive according to claim
 1. 11. A layered product comprising: asubstrate; an adhesive layer consisting of the moisture curable hot meltadhesive according to claim 1 formed on a surface of the substrate; andan adherend adhered to a surface of the adhesive layer.